WTAP–VIRMA counteracts dsDNA binding of the m6A writer METTL3–METTL14 complex and maintains N6-adenosine methylation activity
Xuhui Yan, Feiqing Liu, Junjun Yan, Mengjun Hou, Min Sun, Delin Zhang, Zhou Gong, Dong Xu, Chun Tang, Ping Yin
Abstract
N 6 -methyladenosine (m 6 A) is a prevalent epigenetic modification found in eukaryotic mRNA and plays a crucial role in regulating gene expression in various physiological processes 1 . The m 6 A is installed on mammalian mRNA by a multicomponent methyltransferase complex (MTC) comprising a catalytic subunit (including METTL3 and METTL14) and a regulatory subunit (including WTAP, VIRMA, HAKAI, ZC3H13, and RBM15/15B) 2 . In the catalytic subunit, METTL3 and METTL14 form a stable heterodimer that catalyzes the addition of m 6 A to a preferred consensus RNA motif RRACH (R = A/G, H = A/C/U) 3 . WTAP and VIRMA interact with each other and mediate METTL3–METTL14 localization. Knockdown of WTAP or VIRMA causes substantial impacts on total mRNA m 6 A levels 2 . Structural and biochemical studies have revealed that a quaternary complex called M3–M14–W–V forms, which exhibits significantly higher methylation activity than the METTL3–METTL14 binary complex 4 , 5 . Despite these advances, how WTAP–VIRMA regulates methylation activity remains largely unknown. Here, we show that the METTL3–METTL14 complex possesses promiscuous DNA-binding activity, which disrupts its ability of RNA methylation. Moreover, WTAP–VIRMA counteracts the binding of METTL3–METTL14 to double-stranded DNA (dsDNA) and thus maintains its RNA methylation activity.